As an example of an electronic apparatus, an air conditioner is given. For example, it is ideal that an air conditioner is always operated at an air conditioning temperature that its user feels comfortable. In general, the air conditioning temperature is set by the user using a remote controller, and operation control of the air conditioner is performed so that the set temperature is kept in the room. If the user feels hot or cold, the comfortableness is kept by the user changing the setting of the air conditioning temperature using the remote controller again.
However, if the user does not have the remote controller at hand, the user cannot control the operation of the air conditioner. For example, while sleeping, it may happen that the user cannot have the remote controller nearby or cannot find the remote controller because it is too dark or the user is too sleepy.
A technique is disclosed in which, when it is not possible to operate a remote controller as described above, an air conditioner is controlled on the basis of a user's motion or voice, with the use of an image recognition technique or a voice recognition technique. However, since the user is generally in a dark environment when sleeping, it may happen that the user cannot perform appropriate image processing or that he/she cannot perform voice recognition in consideration of those around the user.
Patent Document 1 discloses a technique in which an external impact is a user input signal, as a technique for transmitting a user instruction to an electronic apparatus without making a loud sound under a dark environment.